Growth of Highly-Ordered-Crystalline Indium-Gallium-Oxide Thin-Film via Plasma-Enhanced ALD for High Performance Top-Gate Field-Effect Transistors.

This study introduces a novel method for achieving highly ordered-crystalline InGaO [0 ≤ x ≤ 0.6] thin films on Si substrates at 250 °C using plasma-enhanced atomic-layer-deposition (PEALD) with dual seed crystal layers (SCLs) of γ-AlO and ZnO. Field-effect transistors (FETs) with random polycrystalline InGaO channels (grown without SCLs) show a mobility (µFE) of 85.1 cm Vs, attributed to high indium content. In contrast, FETs with highly ordered InGaO grown via SCLs exhibit superior performance, with µFE reaching 95.5 cm VVs and enhanced reliability due to the uniform growth of high-quality bixbyite films. The role of γ-AlO and ZnO SCLs in enabling this growth and the correlation between cation composition, crystalline structure, and electrical properties are comprehensively analyzed. This approach provides new insights into the high-quality bixbyite InGaO system, offering an alternative to conventional amorphous or polycrystalline structures. The highly ordered crystalline structure paves the way for advanced applications in 3D heterogeneous semiconductor chips, expanding beyond displays to include memory, logic, and artificial intelligence devices.